PROJECT SUMMARY/ABSTRACT Identification and implementation of clean, sustainable, and affordable catalysis is of paramount importance for both environmental and human health concerns in the future. In addition, catalysis supports technological innovation by providing new materials, chemical reactions and other required building blocks. As the world's population grows, so does the need for natural resources and concerns about the environment, thus society?s dependence on catalysis will also surge. However, many of the most important catalysts are currently based on a few of the least abundant heavy metals in nature, the so called ?precious metals?. The scarcity of noble metals strongly demands the development of alternative base-metals or non-metal catalysts with high-catalytic activity. However designing main group catalysts to have redox properties similar to well-developed precious metal catalysts has remained a challenging task. This proposal outlines a research program dedicated to developing a broad range of catalytic homogeneous reactions for bond activation, atom transfer, and bond forming processes based on structurally deformed phosphorus platforms with nontrigonal molecular geometries. Our ligand platforms are inspired by the entatic states that occur in proteins when a metal or nonmetal is forced into an unusual, energetically strained geometric or electronic state. I propose to develop a new cooperative phosphorus-ligand system that involves a reversible tautomerization process as a driving force to activate small molecules towards the goals of amidation and hydroamination reactions. In addition, structural enforcement of the phosphonium ylide in a C2v environment will mimic properties of transition metal catalysts to perform metal free ring closing metathesis reactions. Ultimately, the frontier of this research proposal is to define the catalytic capabilities of main group elements to perform redox reactions currently dominated by transition metal catalysts. We aim to improve our understanding of factors contributing to the promotion of productive bond activation/functionalization processes, further developing new classes of phosphorus based inorganic catalysts to synthesize value-added commodity chemicals via clean and sustainable reaction routes.